A giant database of people's personal details could be created at Whitehall under government plans which ministers say will help improve public services.
Tony Blair is expected to unveil the proposal in Downing Street on Monday.
Strict regulations currently prevent one part of government sharing personal information it holds with another.
Ministers argue the data-sharing rules are "overzealous" but the Conservatives say relaxing them would be "an excuse for bureaucrats to snoop".
So-called "citizens panels" will gauge public reaction to relaxing privacy procedures so people do not have to repeat personal information to different public bodies - particularly at times of stress such as a family death.